Means and method of exhausting electrical bulbs



Oct. 4,1927. 1,644,002

J. S. VAN HORNE Filed July 25, 1922 Patented Oct. .4, 1927.

UNITED STATES.

, JOHN S. VAN HORNE, OI FRANKLIN, OHIO.

MEANS AND METHOD OF EXHAUSTING ELECTRICAL BULBS.

Applicationmed July 25, 1922. Serial No. 577,454.

T and more particularly to the provision of i and the elimination of Ipoint means and an lmproved mode or process for exhausting such bulbsand tubes, and if the occasion requires refilling them with an inert asor the like without the necessity of leavmg a projecting sprue or teatupon the exterior of the bulb or tube.

In the manufacture of electric li ht bulbs, vacuum-tubes, radioprotectors an the like, it is quite the common practice to use a smallexhaust hole in the wall of the bulb or tube to which is fused the endof a glass exhaust tube, through which the bulb or tube is exhausted bysuitable vacuum or, suction. When the proper degreeof vacuum isattained, the bulb or tube is sealed by burning off or fusingliheexhaust tube at its juncture with the bulb to close the outlet port andseparate the exhaust conduit This process, however, leaves anobjectlonable or sprue such as is ordinarily found at the apex ofincandescent electric lamp bulbs. The present invention is intended toovercome the objectionable features of this method of exhausting suchbulbs and tubes such points or sprues thereby leaving the exterior ofthe glass bulb or tube uniformly smooth, or continuous. Attempts havebeen made to exhaust incan descent lamp bulbs by a glass tube introducedthrough the base of bulb. However, due to the fragile nature of the la sand difliculties of manufacture, the reakage due to the use of suchglass eduction meant, has been so great as to render such processuneconomical and impractical for commercial purposes.

The invention contemplates embedding or sealing into the wall orstructure of the bulb or tube a non-fragile eduction conduit of heatresistant material, preferably, though not necessarily metallic incharacter, which will afford an intercommunicating passage between theinterior and exterior of the bulb or vacuum-tube. When ofelectro-conductive material, this eduction conduit may further serve asone of the electrical conductors. That is to say, a hollow electricalconductor is employed in such embodiment for the double purpose ofcarrying current and of exhausting the bulb or tube. In otherembodiments, such non-fragile or non glass eduction conduit may form thesupporting stalf for the filament anchor in addition to its function inexhausting the bulb or tube or it may be embodied to perform solely andindependently the exhausting function. a

The object of the invention is to simplify the means and mode ofmanufacturing vacuum tubes and electric bulbs, whereby they w1ll notonly be cheapened in construction, but will be uniform in exteriorcontour, de- VOlCl of the usual projecting points or sprue teats,provided with a permanently embodied eduction or exhaust passage andunlikely to get out of repair.

A further object of the invent-ion is to provide means for facilitatingthe exhaust1on of such vacuum tubes and bulbs, and to reduce theincidental breakage, to aminimum.

With the above primary and other incidental objects in view as will morefully appear inthe specification, the invention consists of the featuresof construction, the parts and combinations thereof and the mode ofoperation or their equivalents as hereinafter described and set forth inthe claims.

Referring to the drawings, wherein are shown several preferredembodiments of the invention, Fig. 1 is a side elevation of anincandescent electric light bulb, minus the base cap or screw, to whichthe present invention has been applied. Fig. 2 is an enlargedperspective view of the filament support and electrical connection, theeduction tube forming the subject matter hereof being utilized as thesupporting staff for the filament anchor. Fig. 3 is a side elevation ofan incandescent light bulb wherein the nonfragile, eduction tube formsone of the electrical conductors. Fig. 4 is an enlarged perspective viewof the. filament support, showing a non-fragile eduction tube introducedtherethrough whollv independent of the electrical circuit and filament.Fig. 5 is an enlarged perspective view approximately quadruple size, ofa vacuum tube protector for radio apparatus and the like installationwherein a hollow electrical conductor is employed to exhaust the tube.

Like parts are indicated by similar. characters of reference throughoutthe several views.

In the accompanying drawings, 1 is an ordinary glass incandescent lightbulb, upon which is shown by dotted lines at 2, the pointed teat orsprue wholly eliminated by the present process, leaving the bulb of auninecessarily of metal.

form and continuous peariform shape. This projecting point or sprue onthe end of the bulb as usually manufactured at the present time, is theremains of the glass exhaust tube temporarily connected at this pointduring the manufacture and subsequently removed by burning off or fusingto such extent that it is separated and at the same time sealing theorifice into the bulb.

Located in the base of the bulb is the usual filament support 3,comprising a tube of glass flared at its lower end as at 4 to agree withthe base of the bulb 1 to which it is integrally united by fusing.Extending through this tubular support are the circuit leads orelectrical conductors 5. After the introduction of these lead wires orconductors 5 the upper end of the tubular support 3 is compressed, whilein a plastic or semlfluid condition, thereby embedding the lead wires 5therein. As ordinarily constructed at the present time, commercialincandescent bulbs are provided with an anchor stafi 6 of glass unitedwith the upper end of the support 3 by fusing. Such staff 6 carrles ahead or button 7 in which areembedded the radial supporting arms 8 forthe lighting filament 9. the terminals of which are connected to theconductors or leads 5. In the structure shown in Figs. 1 .and 2, therehas been substituted for the anchor staff 6 a tube 10, of nonfragileheat resistant material. That is to say, material which will resist thedegree of heat necessary for the semi-fusing of the glass tube 3sufficient to render it plastic, that it may be compressed andsolidified about the inserted tubular conduit 10 and circuit leads 5.The glass anchor button 7 is carried upon the upper end of thisnonfragile hollow staff 10. This staff 10 is preferably, though not inthe present instance The tube 10 forming this stall ext-ends downwardlybeyond the base of the bulb 1 and near its upper end is provided with alateral orifice or notch 11, opening into the interior of the bulb 1.Thus after the assembly of the parts, this conduit 10 embedded in thefilament support 3 forms an intercommunicating passage between theinterior and exterior of the bulb, ext-ending through the base thereofthrough which the bulb may be exhausted, and if the bulb is of that typeknown as the gas bulb, the inert gas may be subsequently introducedthrough the same tube. The outer end of this access tube or passagewayis subsequently sealed by burning off or fusing the end of the tube in ahot flame or by other means as is indicated at 12. In the constructionshown in Figs. 1 and 2, the eduction tube is thus made to serve a doublefunction, that of supporting the filament in lieu of the usual glassanchor staff and that of an exhaust conduit through which the bulb isexhausted and if so desired filled with an inert gas.

In Fig. 3 the general construction of the bulb is identical with thatheretofore described except that in lieu of employing the eduction tubeas an anchor staff, the ordinary glass staff as is usual in bulbs ofcommerce is employed, and the eduction tube or exhaust conduit 10, whichin this case is of electro conductive material is employed as one of thecircuit leads in lieu of one of the leads 5 and to which one end of thefilament 9 is connected. Thus in the construction shown in Fig. 3 theeduction tube 10 is in effect a hollow or tubular electrical conductor,which not only carries current to the fila- Inent, but also aliords anexhaust passage through which the bulb may be exhausted, or filled. Thiseduction tube or hollow electrical conductor is likewise sealed by anysuitable sealing plug or material, or is closed by fusing or burning offas at 12.

In Fig. 4 there is shown a modification, wherein the exhaust conduit 10is intro duced by thrusting the same through the side of the supporttube 3, while the latteris in a plastic condition and fusing the glassof the tube 3 into adherence with the conduit.

In this instance the exhaust cond it is lino-functional.

The invention is not only applicable to the manufacture of incandescentlamp bulbs, but is equally as important in the production of vacuumtubes for other purposes, as for instance protector tubes for radiopurposes, as shown in Fig. 5. These tubes ordinarily comprise a glassbulb 14, through each end of which is inserted an electrical conductor.These conductors extend into spaced relation one with the other. Theinterior of the bulb 14: is partially exhausted, the degree ofexhaustion depending upon the condition of use and service required.Current does not ordinarily pass through the protector, but in the eventof excessive voltage the excess current will leak through theintervening gap' from one terminal 'to the other. In the ordinaryprocess of manufacture of such protector tubes for commercial purposes,an external sprue or pointed teat 15 shown byv dotted lines in Fig. 5 isleft. as the remains of the glass exhaust tube severed by fusing orburning off in closing the exhaust port, after the tube has beenexhausted to the desired degree. In order to simplify the manufacture,economize and reduce the number of operations, and above all to minimizethe breakage, the present invention is applied to such vacuum tube bymaking one of the electrical conductors 16 of tubular form. The otherconductor 17 may be an ordinary solid wire conductor. These conductors16 and 17 are Sealed into the ends of the tube 14 by fusing the glassinto adherence to the conductor. The conductor 16 in this case, ofelectro-conductive or metallic material forms an intercommunicatingpassage between the interior and exterior of the tube, through which thetube may be exhausted. After exhaustion, this conductor is closed orsealed either by the introduction of a body of sealing material, or byfusing or burning off, the conductor.

By the use of metallic eduction tubes, or in any event a tube orconduitof non-fragile material, which may or may not form one of thecircuit leads or electrical conductors, the quantity of breakage is notonly materially reduced, but the bulb or tube is left in such conditionthat, in the event that the bulb is not properly exhausted, or if at anysubsequent time the degree of vacuum is to be modified, such conduit oreduction tube may be reopened and the tube or bulb again subjected toexhaustion, or a suitable inert gas or other fluid may be admittedthereto, without endangering the bulb or involving any intricateoperation. By employing the eduction tube as an anchor staff as shown inFigs. 1 and 2, the danger of breakage at this pointis entirelyeliminated.

The tube when of electroconductive charactor. as in Figs. 2 and 5 ispreferably of metal having low resistance and a coefficient of expansionand contraction approximating that of glass, such as is possessed byvarious platinum substitute alloys commonly employed at the present timefor the circuit leads 5 of incandescent lamps. In the event thatnon-metallic or non-conductive material is employed, as in Figs. 1, 2and 4 the material must be one to which the glass will adhere,possessing a fairly high degree of resistance to heat, and likewisehaving a'coefficient of expansion and contraction approximating that ofglass and to which the glass'will adhere, in order that perfect unionmay be maintained between the tube and the glass. Such non-metallictubes having the requisite characteristics may be composed of variousphenolic condensation materials and con'iposition's, or asbestos fibercomposition and the like. These materials and platinum substitute alloysare suggested merely for the purpose of illustration and with no inlr-ntto so limit the invention.

While the invention has been shown applied to an incandescent lamphaving a ring type of filament, it is to he understood that theinvention is equally applicable to other types and for-ms of lamp bulbs,and either gas filled or vacuum tubes of whatever shape or character.

l am aware that heretofore incandescent lamp bulbs have been exhaustedthrough a port provided in the tubular support 3. However, the partsbeing wholly of glass and of small dimensions and extremely fragile,such process has not been generally vention is not adopted forcommercial production, due to the high percentage of breakage. By theuse of non-fragile or metallic tubes as herein described, the exhaustionof lamp bulbs through the base as well as other forms of vacuum tubeswithout leaving the objectionable point or sprue is made entirelypractical and a commercial reality.

From the above description it will be apparent that there is thusprovided a device of the character described, possessing the particularfeatures of advantage before enumerated as desirable, is susceptible ofmodification in its form, proportions, detail construction andarrangement of parts without departing from the principle involved orsacrificing any of its advantages.

Vhile in order to comply with the statute the invention has beendescribed in language more or less specific as to structural features,it is to be understood that the inlimited to the specific details shown,but that the means and construction herein disclosed comprises thepreferred form of several modes of putting the invention into effect andthe invention is therefore claimed in any of its forms ormodificationswithin the legitimate and valid scope of the appendedclaims.

Having thus described my invention, I claim:

1. As an article of manufacture, an electric bulb having a hollowelectrical conductor extending from the exterior to the interior of thebulb is exhausted or filled.

2. As an article of manufacture, a vacuum protector comprising a glassbulb having electrical conductors extending thereinto in spaced relationone with the other, one of said conductors being hollow and throughwhich the bulb is exhausted.

3. As an article of manufacture an electrical bulb, of glass, and atubular electrical conductor leadlng therefrom through which the bulb isexhausted or filled.

4. The herein described method of exhausting glass bulbs and the likeconsisting in sealing a metallic tubular electrical con- (llltftOI' intothe wall of the bulb, exhausting the bulb through such tubular metallicduct and closing the conductor.

5. The herein described method of tubulating lamp bulbs and the likecomprising embedding a non-fragile tube in the wall of the bulb,exhausting the bulb through such tube and subsequently closing the tubeand employing same as an electrical conductor.

In testimony whereof I have hereunto set my hand this th day of July, A.D. 1922.

JOHN S. VAN HORNE.

but which obviously through which the bulb-

